Means for cooling heavy duty motors



Oct. 7, 1952 R. 1. ROBINSON MEANS FOR COOLING HEAVY DUTY MOTORS FiledSept. 11, 1950 m m w E 0 U. P 5 w H heavy dutyelectri'c' motors.

Patented Oct. 7, 1952 R ssen 1.'hdbinsnmmnwauke ,*wisaessien re Iiii-His Gompany,-"Milwaukee, 'Wis., a

I icorpomtiomdi'flwisconsin 3: entean nr m er 11.1e5aiser a 1 arwe Thisinvention relates electric motors and refers more particularly tocooling means for In certain-types of installations electric motors ofrelatively "highfhorsepower operatemnjder irequently varying "load "andspeed conditions so that the usual' cooling "arrangementgconiprising a"fan mounted on "the'rotorifcr rotation there-i with, "isentirely.inadequateflespeciaflly :"si-nce "the rotor is frequentlyoperated at speeds at -winch the air circu1ation"ieffected 'b ythetfranis eta rate less than thatTnormallyreuuire'd for cooling whileat the same time themotor'tendsto heat morethanit ordinarilydo'es.

Extractor motors used in'sugar refineries are an example of anapplication or tyne "of service in which this problem 'hasbeenpartictflarly acute because of the fact that such ine-tors aresub'jected'to constant "acceleration and deceleration sotha't extremelylarge loads are imposed upon them, necessitating the dissipationofflarge amounts ofhea't. p

"In the present invention this dimciiltyis (overcome -by providing aseparate relatively small cooling motor whichrotates the Ianhladestati'a of the ,fact that its rotor/is coaxial with theirotor"ofltheheavy duty motor. 7

Another object of this invention resides in the provision of a heavyduty motor whichisrooled by a separate 'coo'lingmotonwith thejiatterhaving its rotor freely ,rotatahiy mounted. on the heavy-duty motorshaftibymeanszgof'asimple "and compact ,.arrang'ement."df bearings whichenables the rotor of the copiingmotor'tofrotate at 'a'con- 'sta'ntspeed, ie ard1ess of the speediof'thgmain rotor.

With theabove ndotherobfj'ects inviewiwhich will appear as thedescriptionfiproceeds, thisinvention resides in' the 'noveilconstruction, combination and arrangement of partsjsubstantiaily ..ashereinafter described iandi'more' particularly defined by, the appendedfolaimsp'it beingunder stood that ,such changes in" "the preciseembodinrient of "the ghereincliselosed invention maz y he made as-coniewithin the'scbpeoiithe :craims'.

*paratus totbe driven. A wound stator 5, stationcomplete example of thephys'ieai embodiment of *the invention constructed according to the bestmode so far devised for'the practical application off. the principlesthereof --'an-d which:

"The singlefigure is [a iongitudinai sectional view through a heavy dutyelectricmotor constructed in accordance with this invention. I

Referring now to the accompanying drawing, "the-numeral 5 designatesgenerally a housing for aheavyfdutymotor the type which is adapted'toihe subjected to varying *l-o'a'ds and frequent acceleration-anddeceleration; The'housing-has a hat "ba'se ,fi anjd *a'fianged-top Btope-rmit motor to be mounted on either the top or the bo-t tem of a'maehine (notshowm, sue-1'1 asan extra'ctor or the *type usedsugarrefiner' ies, with the motorshaift'i extending vertically-into themachine. For-thispurpese, the motor sh-afit must extend fromfiioth endsef the housing tor connection of either "end ef theshaft with =apar 'flymounted within theuupper portion of the housing, an a squirre'l cagemotor 9, secured to the shaft I by means ofekey "10, comprise thespectively, end-preferably botn :are hail bearings.

The h ubof the-upper :endflaeatl 11 of the motor mousing has a centraltbore IS which'provides a seat for the bearing lfl and a idish.shapedrcover "plate l fi, s'ecured under th hearing seat to the innerfaoeof the hub, provides the bottom of an eil reservoir tor the fiballbearing; the top of the oi-1' re'servoir 'beihg closed byan oppositelydished '-cover'ip1ate"|'=1 secured.to'the outer face of the hub-of theend belL- h censta'n tfiow ofluhricant "to the' bearing H isprovided hymeans of oil ducts-(not shown connected 1-9 in eachcover plate.

- The shaft, or course, passes through the ceninto a tapped port "tr'albore in -'each cover plate, and oil leakage along'theashaft, ifromithetnt'erior'hf the reservoir defined by the two-cover piates lfi and I1and "the bore I 5 in the -end Eben; Eisprec luded by means--'of-=o'i1sea1s 18in the bores of the cover plates. "The in'njer' race'or'the hearing 1H 'is clamped hetween ashouider :2 I on the emit,defined lby za reduc'tion'in "the diameter of "(the :shaft above "theshoulder, and -a"'-nut 32.2 threaded onto the vsinrflarifiinconstruction :to lthatitor the upper The "accompanying "drawing"illustrates 'one main bearmg aicept th'at iits 'npperT-Jan'd lowerreservoir covers 23 and 24, respectively, define a pair of opposedshoulders 25 and 28 which are spaced apart a distance equal to the axiallength of the outer race of the lower main bearing 12 and thus lock thishearing race between them to hold the bearing against axialdisplacement.

Since the inner race of the lower main bearing is clamped between anut22'f'threaded onto the shaft and a shoulder 28 on the shaft, in a mannerto be described presently, the lower main bearing 12 serves as a thrustbearing to hold the" shaft against shifting axially. The upper 'main'bearing, however, is not held against axial dis-' placement, toaccommodate any differences the rates of thermal expansion ofthejsha'ft" and the housing. 1

The upper reservoir cover 2 3 for the lower main bearing also providesthe lower-end bellof a cooling motor 29 which occupies the lower;

36 and a bottom fan bearing, 31. These bearings journal 4 the sleeve onf the shaft; JAnup wardly facing shoulder 38 inthe upper receptacle 34engages the outer race of the top fan bearing 36 and cooperates with adownwardly-facing shoulder 39 on the shaft (defined by a reduceddiameter portion thereof), whichg engages the top of the inner race, topreclude upward .axial displacement of the sleeve with respect to theshaft. Downward displacementof the'sleeve ,is

prevented by a, downwardly facin shoulder 40 in the lower bearingreceptacle which engages the outer race of the bottom fan bearingjlandby supporting the inner raceof said bearingin a manner now about to bedescribed. v v

A second downwardly facing shoulder 221 on the lower portion of theshaft is definegi byv a portion of the shaft therebelow havingafurtherreduced diameter, and a short spacer sleeve 43 is interposed betweenthis shoulder and the top.

of the inner race of the bearing ill. Another spacer sleeve 44 isinterposed between'theinner races of the bottom fan bearing 31 and themain bearing 12. The nut 22' and the shoulder. cooperate with thesespacer sleeves to, clamp the inner races of these two bearings, inaxially spaced apart relationship, fixed with respect to one anotherandthe shaft. Since, as has-already been pointed out, the outer;race.ofthe lower main bearing l2-is secured between the top and bottomcovers 23 and 24 of ,the lower oil reservoir, securement ofthe, shaft toits inner race in this manner enables the lower main bearing to hold theshaft against, axial displacement.

The upper bearing receptacle 3,4, in addition to serving as a seat forthe bearing 35 also provides a mounting for an impeller- ;44.;, The; hub45 offthe impeller fits over and is, fixed gto the bearing receptaclei34by SGV'SCIBWSLQE8415133. key. 41. The ,hub is substantially dome:fihaped and the fan blades 48 radiate; therefrp .ahiam preferably castintegrally therewith.-

Cooling air for the motor is taken n;to; the housing through air ports,49 ,near the- -bottom thereof, the inlets being provided withgscreens.

(between. f L2( .The.

50 to prevent the entry of foreign matter into the motor mechanism.Since the frame of the cooling motor is merely a support for the statorrather than a complete housing, air drawn into the motor housing willtend to circulate across the cooling motor to thus maintain it at a lowtemperature, .although it will be understood that c'oolinfg ofthe fanmotor is notaserious problem because of its small size and constantspeed. Since the rotor of the cooling motor drives the fan blades at aconstant speed, cooling air will he drawn"into the housing at a constantrate and will at all times be impelled upwardly acrossthe heayydutymotor so long as the coolmotoriifie f nmng. It will be noted that the11011511181431 the,-heavy duty motor provides air passages 5 l aroundthe stator thereof to assure adequate cooling and that the air leavesthe housing through outlet ports 52 in the upper end bell.

vIn order to minimizeIrelative rotation between the .oo gmotorf enafthemain motor, the two rotors turn'in the same direction and preferablyrotate at. the same speeds when both are operatms a the r f ll Synchroou p d 'Froniithefforegoing description; taken together withthegcconipanyingdrawing, it will be readily apparent, thatthisi'nvention provides a simple andfcoinpact cooling device for a heavyduty gm'otorof theitype which is subjected to frequent accelerationsan'd -decelerations.

f,- 1What vI claim as my invention is:

-1.1I'n a heavyfduty electric "motor having a housing'provided withventilating openings adjacent to-its opposite ends,"a heavy duty motorfinon e'jefndportion of jthehousing, an impeller eqiiippd icooling motorin; the other end portionjofgth'e housingeaonor said motors includi'n'gla s t'atoglwith respect to the housing and an armature encircledjby thestator, char- .acteri'zed by'fjthe provision of a single motor'shaftenc'ircled by" said ar'maturesjand journalled in bearings ontheends of the housing, and having the armature ofthe, heavy duty motorfixed thereto; asleeve rotatably journalled on the motorjshaftbybearings confined between the shaft,and thefwallsf of. bearing hubsformed on the ends or 'the'sle'eve; s'aidfsleeve having the armaturebftheco'oling motor "fixed to its exterior, smiths-impeller being mountedon the ee iii i uhgorthe sleeve adjacent to the heavy 'dutymotomfandfa'frame upon which the stator or -"the toqli ng .mo'tor isjm'ounted, saidframe ei'hgiseoured to .the end of the housing re- 55,

motef fromT'thejjheavy duty motor and being radially spaced fromthelsurrounding' housing walls to perm it the pass'age of cooling airthere- I I eavyfduty electric motor set forth in claim;'1", wh f mthel'ends" of the motor housin areQ 'substant 11 serene normal to theaxis of l the rotor". shaft" to provide for mounting the fmotorgwith'therotorfshaftivertical; and further .characteriiedfby. the fact thatthe rotor shaft projects outwardly' byond each end of the motor housingso that either end of the shaft may be connected. with. a paratus to bedriven. 3.In.. a. heavyjduty'electric motor having a and'an i 'armatureencircled by the'stator, char- 5 acterized by the provision of: a.single motor shaft encircled by said armatures and journaled in hearingson the ends of the housing, and having the armature of the heavy dutymotor fixed thereto; a sleeve rotatably journaled on the motor shaft andhaving the armature of the cooling motor fixed to its exterior, and theimpeller being mounted on the end portion of the sleeve adjacent to theheavy duty motor; and a frame upon which the stator of the cooling motoris mounted, said frame being secured to the end of the housing remotefrom the heavy duty motor and being radially spaced from the surroundinghousing walls to permit the passage or the cooling air therebetween.

RUSSELL I. ROBINSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

6 UNITED STATES PATENTS Number 15 Number

